The invention relates to a clutch-and-brake unit.
The generally-known clutch-and-brake unit of the type in question comprises a brake disk and a clutch disk which can be brought into frictional engagement with brake and clutch pressure plates independently of each other. The clutch and brake disks are either of rigid construction and slidable along splines on the driven shaft, or axially fixed to the driven shaft and constructed to be axially resilient. To provide two such disks is costly with respect to both design and production and also requires much space. Since such drives are engaged and disengaged with extremely high frequency (there may be as many as 30,000 clutch and brake operating cycles in the course of an eight-hour work shift), it is also important that the operating noise be minimized.
From German patent application No. DOS 22 31 501, an electromagnetically actuable clutch-and-brake unit is known in which a clutch disk on a driven shaft is secured against rotation relative thereto but axially displaceable. It is provided with a clutch facing on one side and is adapted to be brought into engagement with a rotating clutch pressure plate, for example, the flywheel of a motor, when a clutch magnet is energized. On its other side, the clutch disk is provided with a brake lining which by means of initially tensioned springs is brought into engagement with a brake pressure plate that is fixed to the housing. Now such a design is not suited for a control drive of the type in question since it does not permit controlled braking. Moreover, considerable operating noise is generated.
From Canadian Pat. No. 749,148, a clutch-and-brake unit of the type in question is known in which the clutch coil and the brake coil are disposed in an outer bearing bracket which serves both as clutch bearing bracket and as brake bearing bracket.